1. Field of the Invention
The present invention relates generally to medical devices and methods configured for the treatment of bone fractures, and more particularly, to a system and method for intramedullary subchondral support fixation (IMSSF) of radial head fractures.
2. Description of the Prior Art
In the medical arts, there is increasing awareness regarding the relevance of radial column integrity across the spectrum of elbow injuries. Cadaveric studies have supported the view that an intact radial head provides secondary support to the elbow joint in valgus stress. When there is compromise to the medial collateral ligament, the main buttress against valgus deviation is provided by the radial head. The in-vitro varus-valgus laxity after ligament disruption is further increased after radial head excision. Restoration of the radial head using radial head arthroplasty, for example, must be carried out in combination with ligament repair to restore normal elbow stability.
The specific lesions in the so-called “unhappy triad” include medial collateral ligament tear, coronoid fracture and radial head fracture. The combination of these injuries renders the elbow joint unstable with the potential for early advanced joint degeneration and deformity. A number of studies have been performed relating to the issue of posterolateral instability in cadaveric specimens with intact collateral ligaments after radial head excision in combination with coronoid lesions. These studies emphasize the key role of the radial column. In the studies, the degree of rotational displacement of the ulna was measured after a valgus-supination moment was applied. Excision of the radial head significantly destabilized the elbow in posterolateral testing. Frank ulnohumeral dislocation takes place with excision of greater than 30% of the coronoid. Only restoration of the radial head can stabilize the elbow, provided the collateral ligaments remain intact. In radial head fracture cases, it is therefore desirable to restore the radial head whenever possible.
A wide variety of devices have been developed for the support and treatment of various bone fractures, and more particularly, the support and treatment of radial head fractures. A common approach which is currently used to treat radial head fractures is open reduction and internal fixation of radial head fractures.
Open reduction and internal fixation of radial head fractures frequently requires the application of a plate in the non-articular (non-cartilagenous) portion of the fractured head. In most instances, proper exposure of the fractured head requires the release and later repair of the key ligamentous structures. One of those important structures requiring release is the annular ligament. It is desirable to avoid dividing this ligament because it is critical to the stability of the proximal end of the radius. In addition, standard plating techniques frequently fail to meet the mechanical requirement for physiological loads which are applied to the radial head throughout the range of motion of the radius. Recent advances in the current art for fixation methods of radial head fractures have included modular fixed angle assembly techniques, in which bone screws are extended through a plate placed on the non-articular portion of the fractured head and into the head. Because these current art plates are applied to the surface of the bone, their use requires release of important ligaments such as the annular ligament and also results in significant hardware irritation of the surrounding soft tissues. This frequently requires re-operation to ameliorate the effects of irritation. In addition, the current art plates continue to interfere with normal rotation of the radial head in its articulation. Moreover, current plate fixation techniques require that the plate be placed directly on top of the bone and soft tissue sleeve, and this compresses the tenuous blood supply to the radius.
In current plate fixation technology, the plate is often a significant source of irritation to the annular ligament, as the plate lies under the repaired annular ligament. Additionally, current art plates are typically not able to be utilized in such a manner as to preserve the tenuous periosteal sleeve.
In this respect, there is a need in the art for a system and method for intramedullary subchondral support fixation (IMSSF) of radial head fractures which addresses the disadvantages present in existing fixation systems and methods.